max_vars(3).
max_body(3).
max_clauses(6).

enable_pi.
enable_recursion.

% head
head_pred(target,2).
% body_pred(target,2).
body_pred(parent,2).

% type(target,(element,element)).
% type(target,(element,element)).
% type(parent,(element,element)).

% direction(target,(in,out)).
% direction(target,(in,out)).
% direction(parent,(in,out)).